Step 1. Preheat the oven to 425 degrees Fahrenheit. If desired, line a large, rimmed baking sheet with parchment paper for easy cleanup.

Next step is, On the baking sheet, toss the cauliflower with 2 tablespoons of the olive oil until lightly and evenly coated in oil. Arrange the cauliflower in a single layer and sprinkle lightly with salt. Bake until the cauliflower is tender and caramelized on the edges, 25 to 35 minutes, tossing halfway.

After that, Once the cauliflower is almost done, in a Dutch oven or soup pot, warm the remaining 1 tablespoon olive oil over medium heat until shimmering. Add the onion and ¼ teaspoon salt. Cook, stirring occasionally, until the onion is softened and turning translucent, 5 to 7 minutes.